The present invention relates to a lens assembly for optical scanners which greatly improves the effective area of illumination.
FIGS. 1(a) and 1(b) show a lens assembly for optical scanners according to the prior art in which the lens which condenses the light of the light emitting diode array onto a document has a convex top surface. When the lens assembly is installed, the distance between an object and the convex top surface of the lens is maintained at about 6 mm, and the effective area of illumination .DELTA.L is about 1.8-2.0 mm. Because of limited effective area of illumination, the adjustment of the optical mechanism is important during the manufacturing of fax machines, scanners, contact image sensors. However, because the adjustment of the optical mechanism is complicated, the manufacturing cost of the fax machines, scanners, contact image sensors is relatively increased.